Method for producing a molded part and a molded part produced according to said method

ABSTRACT

The invention relates to a molded part ( 10 ) which is configured by initially forming a tubular body ( 2 ) with a soldered flange ( 7 ). Subsequently, the body ( 2 ) is shaped in a mold ( 8 ) by securing the flange ( 7 ) under high internal pressure to shape the form part or the preform ( 10 ). Thus, preforms with a secured flange that can be used to connect said preforms to other parts can be easily obtained.

[0001] The invention relates to a method for the production of a formedsheet-metal component which is formed by internal high-pressure forming.The invention also relates to a formed component produced according tothe method.

[0002] It is known to shape components by internal high-pressure formingof butt-welded tubular preforms which are cut from corresponding barstock to the length required. From EP-A-0620056 it is also known to weldtogether a number of such butt-welded tubular preforms of differentdiameter and thickness into a single tube which is then formed into atubular component by internal high-pressure forming.

[0003] Extended formed components made from tubular preforms mayespecially be used as components in motor vehicle construction. Here,these components usually have to be joined to other components, eg. byfurther welding or by bonding. For certain purposes, it is thennecessary for one component to be provided with at least one attachmentflange. At least one operation is required to add such a flange to thesaid components, which is a disadvantage in terms of cost, so that, inthis case, several components formed by deep-drawing or pressing areusually welded together in a conventional manner into one formedcomponent.

[0004] Therefore, the problem which the invention by internalhigh-pressure forming, provides a component which can easily be producedand be joined to other components.

[0005] This problem is solved by the characterising features of claim 1.

[0006] By firstly forming a body with an outwardly directed flange,production is facilitated, since the flange serves as a welding flangewhich can be welded by conventional low-cost methods at a high rate ofproduction. In the completed formed component, this already existingflange serves as an attachment point for other components, which makesthe use of such a formed component advantageous in many applications incomparison with conventional bodies formed by internal high-pressureforming.

[0007] Another object of the invention is to provide a component formedby internal high-pressure forming which can be easily joined to other acomponents. This problem can be solved by a formed component accordingto claim 9.

[0008] Embodiments of the invention will now be described in detail byway of example, with reference to the drawings, in which:

[0009]FIGS. 1a-1 e show schematically the steps in the production of aformed component produced in accordance with the invention;

[0010]FIG. 2 shows in profile a formed component according to theinvention, and its use as a roof edge section for a motor vehicle;

[0011]FIG. 3 shows in profile a formed component according to theinvention, and its use as a door sill section for a motor vehicle;

[0012]FIG. 4 shows in profile a formed component according to theinvention, and its use as a door post for a motor vehicle;

[0013]FIG. 5 shows in profile a formed component according to theinvention, and its use as a hinge bracket or lock bracket for a motorvehicle; and

[0014]FIG. 6 shows a further embodiment of formed component according tothe invention prior to internal high-pressure forming.

[0015]FIGS. 1a-1 e show schematically a sequence of process steps in theproduction of a formed component or body according to the invention. InFIG. 1a, 1 denotes a sheet-metal blank from which the body will beformed. This blank 1 may be homogeneous, eg. a wholly steel or aluminiumblank consisting of a single piece of the requisite size and withuniform thickness, as illustrated in FIG. 1a. The blank may, however,consist of two or more sheet-metal portions joined together by welding,so that the blank 1 has portions of different thickness and/or withother dissimilarities of material characteristics or properties, whichimpart to the subsequent formed component local differences incharacteristics or properties. Such blanks consisting of portions joinedtogether (so-called tailored blanks) are known, and are used eg. inmotor vehicle construction, where they are formed into components in aknown manner. The “tailored blank” can be assembled in any desireddirection and using any desired welding processes.

[0016] As shown in FIG. 1b the blank is formed into an essentiallycylindrical tube 2, two margins 3 and 4 of the blank being formed intotongues projecting from the tubular part 2, these tongues togetherconstituting a flange 7 projecting from the tube. The forming of theblank 1 into the tubular part 2 may be performed on a rounding machinein a conventional manner, with unrounded margins 3,4 forming thetongues.

[0017] Fabrication of the tubular body 2 continues with the weldingtogether of the tongues 3,4 to constitute the flange 1 (FIG. 1c). Thismay be performed eq. by lap seam welding with welding rollers 5 and 6, awire electrode being provided in a known manner at each of the weldingrollers 5,6. This has the advantage that coated metal blanks, eg. tinnedor galvanized blanks, can be welded without any problem, as the wireelectrode is continuously replenished from a spool. Alternatively theflange 7 may be welded eg. by edgewise laser welding, as illustrated inFIG. 1c by the additional arrow A symbolically representing the laserbeam impinging on the tongues 3,4. Both roller seam welding and laserbeam welding allow lengthy flanges 7 to be continuously welded at a highrate of feed and with high weld quality. It is also possible to employlaser welding in which the flange is through-welded from above or below.Alteratively the margins may be joined together edgewise by other knownwelding processes such as MIG, MAG, plasma or oxyacetylene welding.Electron-beam welding is also possible. By employing these processes,practically all kinds of sheet metal including, in particular, coatedsheet-metal blanks, can be welded with high quality. The welded body 2has an essentially tubular form with open ends and with a sealinglywelded flange 7.

[0018] In a next step (FIG. 1d) the body 2 thus formed is placed in amould 8 for internal high-pressure forming. The inner surface of thismould has a configuration which corresponds to the shape of the formedbody to be produced. The mould also has means for closing off the openends of the tubular body 2 and means for introducing—usually via theend—a fluid at high pressure. The fluid for forming may also beintroduced through an orifice or nozzle within the cylindrical portionof the preform. The process of internal high-pressure forming is knownin itself and the corresponding devices for carrying out this processare likewise known and available on the marker, and will therefore notbe described in further detail here. In the present case, however themould 8 is configured so that the flange 7 can be clamped in the mouldby the mould itself or by additional means, so that the flange 7 isimpinged on both faces, over as nearly as possible its entire length,and preferably its full width, during the internal high-pressure formingprocess, so that the weld seam of the flange is not subjected to openingor pealing forces due to the pressure exerted in the interior of thebody 2.

[0019]FIG. 1e shows the resulting formed body 10, which has the desiredshape imparted by internal high-pressure forming, and is provided with aflange 7 which can be used for attaching be body 10 to anothercomponent.

[0020]FIG. 2 shows as an example a formed body 11 which has beenproduced by the steps 1 a to 1 e described above, used as a roof edgesection for a car roof 15. FIG. 2 shows this application in schematicand highly simplified form. It will be seen that the formed body 11 isattached to the roof 15 by its flange 7, eg. by a laser-welded joint(seam 16). Of course, other known attachment techniques (such as spotwelding or bonding) might be employed.

[0021]FIG. 3 shows a further formed body 12 produced in accordance withthe invention. This body—likewise shown only in simplified form—is usedas a door sill section for a motor vehicle. 17 denotes a part of thevehicle floor to which the formed body 12 is attached by the flange 7,eg. by spot welding or laser welding.

[0022]FIG. 4 shows schematically an end view of a formed body 13according to the invention, which can be used as a door post (B-pillar)of a motor vehicle.

[0023]FIG. 5 shows a further formed body 14 fitted as a formed sectionin the hinge or lock region of a car engine bonnet or boot lid. Theformed body 14 is attached by the flange 7 to the bent-over end 21 ofthe outer skin 19 of the bonnet or lid. The inner skin is fitted to theouter skin on interposed rubber mountings, and stiffeners 22 areprovided.

[0024]FIG. 6 shows a tubular body 25 made up of two half-round formedblanks 26 and 27. Each blank has two projecting margins or tongues whichare paired to provide flanges 28 and 29. These are welded as describedabove with reference to the flange 7 of FIG. 1. The body 25 is alsoformed by internal high-pressure forming, the two flanges 28 and 29being gripped over as nearly as possible their entire area. Afterforming, a formed body 30 with two flanges 28 and 29 results.

[0025] Of course, the method according to the invention can be used forproducing a large number of formed components for other applicationsbesides motor vehicle construction, such as eg. railcar building oraircraft construction.

1. Method for the production of a formed sheet-metal component(10-14,30) characterised in that a body (2;25) is formed from at leastone sheet-metal blank (1;26,27), with at least one flange (7;28,29)directed outwardly from the body formed from margins (3,4) of the blankin that the flange is welded, and in that the body is formed into theformed component (10-14;30) by internal high-pressure forming.
 2. Methodaccording to claim 1 , characterised in that the flange (7;28,29) inwelded by roller seam welding with or without wire electrode.
 3. Methodaccording to claim 1 or claim 2 , characterised in that the flange iswelded by laser welding or electron beam welding.
 4. Method according toclaim 1 , characterised in that the flange is welded by gas fusionwelding or electric arc welding.
 5. Method according to any one ofclaims 1 to 4 , characterised in that the flange is clamped during theinternal high-pressure forming, in particular by the mould (8) for theinternal high-pressure forming.
 6. Method according to any one of claims1 to 5 , characterised in that the body (2) is formed by rounding asheet-metal blank (1) into an essentially tubular shape.
 7. Methodaccording to any one of claims 1 to 5 , characterized in that the body(25) is foamed from two sheet-metal blanks by providing two flanges(28,29).
 8. Method according to any one of claims 1 to 7 , characterisedin that each sheet-metal blank (1) is composed of at least two blankswhich are assembled together by welding.
 9. Formed component (10-14;301of sheet metal, produced by the method according to claims 1 to 8 . 10.Formed component according to claim 9 , characterised in that it is aroof edge section (11) for motor vehicle construction.
 11. Formedcomponent according to claim 9 , characterised in that it is a door sillsection (12) for motor vehicle construction.
 12. Formed componentaccording to claim 9 , characterised in that it is a pillar (13) formotor vehicle construction.
 13. Formed component according to claim 9 ,characterised in that it is a hinge bracket or lock bracket (14) formotor vehicle construction.
 14. Formed component according to claim 9 ,characterised in that it is a longitudinal beam or transverse beam formotor vehicle construction.